Transmission of acknowledgement signals in a communication system

ABSTRACT

Methods and apparatuses are provided for transmitting hybrid automatic repeat request acknowledgement (HARQ-ACK) information by a terminal in a wireless communication system. A method includes receiving one or more transport blocks, determining a number of HARQ-ACK bits in response to the one or more transport blocks, determining an uplink resource for transmission of the HARQ-ACK bits, and transmitting the HARQ-ACK bits by using the determined uplink resource, wherein the uplink resource is associated with a first modulation order or with a second modulation order, different from the first modulation order, depending on the number of HARQ-ACK bits.

PRIORITY

This application is a Continuation Application of U.S. patentapplication Ser. No. 14/802,348, filed in the U.S. Patent and TrademarkOffice on Jul. 17, 2015, which is a Continuation Application of U.S.application Ser. No. 13/263,233, filed in the U.S. Patent and TrademarkOffice on Oct. 6, 2011, now U.S. Pat. No. 9,112,689, issued on Aug. 18,2015, which is a U.S. National Stage Application of InternationalApplication No. PCT/KR2010/001541, filed on Mar. 11, 2010, which claimspriority to U.S. Provisional Application No. 61/159,229, filed on Mar.11, 2009, the contents of each of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention is directed to wireless communication systems and,more specifically, to the transmission of acknowledgment signals in theuplink of a communication system.

2. Description of the Related Art

A communication system consists of the DownLink (DL), conveyingtransmissions of signals from a base station (Node B) to User Equipments(UEs), and of the UpLink (UL), conveying transmissions of signals fromUEs to the Node B. A UE, also commonly referred to as a terminal or amobile station, may be fixed or mobile and may be a wireless device, acellular phone, a personal computer device, etc. A Node B is generally afixed station and may also be referred to as a Base Transceiver System(BTS), an access point, or some other terminology.

The UL signals consist of data signals, carrying the informationcontent, control signals, and Reference Signals (RS), which are alsoknown as pilot signals. The UEs convey UL data signals through aPhysical Uplink Shared CHannel (PUSCH). The UL control signals includeacknowledgement signals associated with the application of HybridAutomatic Repeat reQuest (HARD) and other control signals. A UEtransmits an HARQ-ACKnowledgement (HARQ-ACK) signal in response to thereception of Transport Blocks (TBs). Depending on whether the receptionof a TB is correct or incorrect, the respective HARQ-ACK bit is an ACKor a NAK which can be respectively represented by a bit value of “1” ora bit value of “0”. The HARQ-ACK signal is transmitted over aTransmission Time Interval (TTI) either in a Physical Uplink ControlCHannel (PUCCH) or, together with data, in the PUSCH.

An exemplary structure for the PUCCH transmission in a TTI, which forsimplicity is assumed to consist of one sub-frame, is shown in FIG. 1.The sub-frame 110 includes two slots. Each slot 120 includes N_(symb)^(UL) symbols used for the transmission of HARQ-ACK signals or ReferenceSignals (RS). Each symbol 130 further includes a Cyclic Prefix (CP) tomitigate interference due to channel propagation effects. The PUCCHtransmission in the first slot may be at a different part of theoperating BandWidth (BW) than the PUCCH transmission in the second slot.Some symbols in each slot can be used for RS transmission to providechannel estimation and enable coherent demodulation of the receivedHARQ-ACK signal. The transmission BW is assumed to consist of frequencyresource units which will be referred to as Physical Resource Blocks(PRBs). Each PRB is further assumed to consist of N_(sc) ^(RB)sub-carriers, or Resource Elements (REs), and a UE transmits itsHARQ-ACK signals over one PRB 140 in the PUCCH.

An exemplary structure for the HARQ-ACK signal transmission in one ofthe sub-frame slots is illustrated in FIG. 2. The transmission structure210 comprises of HARQ-ACK signals and RS to enable coherent demodulationof the HARQ-ACK signals. The HARQ-ACK bits 220 modulate 230 a “ConstantAmplitude Zero Auto-Correlation (CAZAC)” sequence 240, for example withBinary Phase Shift Keying (BPSK) for 1 HARQ-ACK bit or with QuadraturePhase Shift Keying (QPSK) for 2 HARQ-ACK bits which is then transmittedafter performing the Inverse Fast Fourier Transform (IFFT) operation asit is subsequently described. Each RS 250 is transmitted through theunmodulated CAZAC sequence. The signal transmission in FIG. 2 iscontiguous in frequency and is referred to as Single-Carrier (SC)transmission.

An example of CAZAC sequences is given by

${c_{k}(n)} = {\exp \left\lbrack {\frac{j\; 2\pi \; k}{Z}\left( {n + {n\frac{\; {n + 1}}{2}}} \right)} \right\rbrack}$

where z is the length of the CAZAC sequence, n is the index of anelement of the sequence n={0, 1, . . . , Z−1}, and k is the index of thesequence. If Z is a prime integer, there are Z−1 distinct sequenceswhich are defined as k ranges in {0, 1, . . . , Z−1}. If the PRBscomprise of an even number of REs, such as for example N_(sc) ^(Rb)=12REs, CAZAC sequences with even length can be directly generated throughcomputer search for sequences satisfying the CAZAC properties.

FIG. 3 shows an exemplary transmitter structure for a CAZAC sequencethat can be used without modulation as RS or with BPSK or QPSKmodulation as HARQ-ACK signal. The frequency-domain version of acomputer generated CAZAC sequence 310 is used. The REs corresponding tothe assigned PUCCH BW are selected 320 for mapping 330 the CAZACsequence, an IFFT is performed 340, and a Cyclic Shift (CS) applies tothe output 350 as it is subsequently described. Finally, the cyclicprefix (CP) 360 and filtering 370 are applied to the transmitted signal380. Zero padding is assumed to be inserted by the reference UE in REsused for the signal transmission by other UEs and in guard REs (notshown).

Moreover, for brevity, additional transmitter circuitry such asdigital-to-analog converter, analog filters, amplifiers, and transmitterantennas as they are known in the art, are not shown. The reverse(complementary) transmitter functions are performed for the reception ofthe CAZAC sequence. This is conceptually illustrated in FIG. 4 where thereverse operations of those in FIG. 3 apply. An antenna receives RFanalog signal and after further processing units (such as filters,amplifiers, frequency down-converters, and analog-to-digital converters)the digital received signal 410 is filtered 420 and the CP is removed430. Subsequently, the CS is restored 440, a Fast Fourier Transform(FFT) 450 is applied, and the transmitted REs 460 are selected 465. FIG.4 also shows the subsequent correlation 470 with the replica 480 of theCAZAC sequence. Finally, the output 490 is obtained which can then bepassed to a channel estimation unit, such as a time-frequencyinterpolator, in case of a RS, or can to detect the transmittedinformation, in case the CAZAC sequence is modulated by HARQ-ACK bits.

Different CSs of the same CAZAC sequence provide orthogonal CAZACsequences. Therefore, different CSs of the same CAZAC sequence can beallocated to different UEs in the same PUCCH PRB and achieve orthogonalmultiplexing for the respective HARQ-ACK signal transmissions. Thisprinciple is illustrated in FIG. 5. In order for the multiple CAZACsequences 510, 530, 550, 570 generated correspondingly from multiple CSs520, 540, 560, 580 of the same root CAZAC sequence to be orthogonal, theCS value Δ 590 should exceed the channel propagation delay spread D(including a time uncertainty error and filter spillover effects). IfT_(s) is the symbol duration, the number of such CSs is └T_(s)/D┘, wherethe └ ┘ (floor) function rounds a number to its previous integer.Orthogonal multiplexing can also be in the time domain using OrthogonalCovering Codes (OCC). The symbols for HARQ-ACK and RS transmission ineach slot are respectively multiplied with a first OCC and a second OCCbut further details are omitted for brevity as these multiplexingaspects are not material to the invention. The number of resources in aPUCCH PRB is determined by the product of the number of CS for the CAZACsequence times the OCC length. For 6 CS, length 4 OCC for the symbolsused for HARQ-ACK signal transmission, and length 3 OCC for the symbolsused for RS transmission, the number of resources for HARQ-ACK signalingin a PRB is 6×3=18 (the smaller OCC length applies).

A UE can determine the PUCCH resource (PRB, CS, OCC) for its HARQ-ACKsignal transmission either through explicit indication from its servingNode B or through implicit indication. The latter can be based on theresources used for the transmission of the Scheduling Assignment (SA) inthe Physical Downlink Control CHannel (PDCCH). The SA configures theparameters for the reception by the UE of TBs in response to which theUE subsequently transmits an HARQ-ACK signal. An exemplary PDCCHtransmission considers that the REs carrying each SA are grouped intoControl Channel Elements (CCEs). For a given number of SA informationbits, the number of CCEs depends on the channel coding rate (QPSKmodulation is assumed). For a UE with low Signal-to-Interference andNoise Ratio (SINR), the Node B may use a low channel coding rate toachieve a desired BLock Error Rate (BLER) while it may use a high codingrate for a UE with high SINR. Therefore, a SA may require more CCEs forits transmission to a low SINR UE. Typical CCE aggregation levels followa “tree-based” structure consisting, for example, of 1, 2, 4, and 8CCEs.

FIG. 6 further illustrates the PDCCH transmission using CCEs. Afterchannel coding and rate matching of the SA information bits (not shown),the encoded SA bits are mapped to CCEs in the logical domain. The first4 CCEs, CCE1 601, CCE2 602, CCE3 603, and CCE4 604 are used for the SAtransmission to UE1. The next 2 CCEs, CCE5 611 and CCE6 612, are usedfor the SA transmission to UE2. The next 2 CCEs, CCE7 621 and CCE8 622,are used for the SA transmission to UE3. Finally, the last CCE, CCE9631, is used for the SA transmission to UE4. After further processingwhich can include bit scrambling, modulation, interleaving, and mappingto REs 640, each SA is transmitted in the PDCCH 650.

At the UE receiver, the reverse operations are performed (not shown forbrevity) and if the SA is correctly decoded, the UE proceeds to receivethe TBs. A one-to-one mapping exists between the PUCCH resources forHARQ-ACK signal transmission and the CCEs used for the SA transmission.For example, if a single PUCCH resource is used for HARQ-ACK signaltransmission, it may correspond to the CCE with the lowest index (firstCCE) for the respective SA. Then, UE1, UE2, UE3, and UE4 userespectively PUCCH resource 1, 5, 7, and 9 for their HARQ-ACK signaltransmission. If all resources within a PUCCH PRB are used, theresources in the immediately next PRB can be used. The first PUCCH PRBfor HARQ-ACK signal transmission may be informed by the serving Node Bthrough broadcast signaling. In order to support higher data rates andimprove the spectral efficiency relative to legacy communicationsystems, BWs larger than the ones of Component Carriers (CCs) for legacysystems are needed. These larger BWs may be achieved by the aggregationof multiple legacy CCs. For example, a BW of 100 MHz may be achieved byaggregating five 20 MHz CCs. The reception of TBs in each DL CC isconfigured by a respective SA as described in FIG. 6.

Each DL CC is associated with an UL CC which contains respectiveresources for the HARQ-ACK signal transmission. In case each differentDL CC is linked to a different UL CC, the resources for HARQ-ACK signaltransmission may be as for the legacy systems. In case multiple DL CCsare linked to the same UL CC for HARQ-ACK signal transmission, separateresources may be pre-assigned in the UL CC for the transmission ofHARQ-ACK signals in response to TBs in each of the DL CCs. This isfurther illustrated in FIG. 7 where two DL CCs, 710 and 720, are linkedto one UL CC 730 and the resources for the HARQ-ACK signal transmissionin response to TBs transmitted in the first DL CC are always in a firstset of UL resources 740 while the resources for the HARQ-ACKtransmission in response to TBs transmitted in the second DL CC arealways in a second set of UL resources 750.

The conventional approach for a UE to transmit HARQ-ACK signals inresponse to the reception of TBs in multiple DL CCs is to simply extendthe HARQ-ACK signaling method in case of a single DL CC andsimultaneously transmit multiple HARQ-ACK signals, each corresponding toa DL CC. The main disadvantage of this approach stems for the limitationin the maximum UE transmission power. Simultaneous transmission ofmultiple HARQ-ACK signals increases the peak-to-average power ratio(PAPR) of the combined signal transmission as the single-carrierproperty is not preserved. Also, channel estimation becomes worse as theRS power is distributed in multiple resources and the total interferenceis increased as HARQ-ACK signals are transmitted in multiple resources.

In order to address the previous shortcomings for the transmission ofmultiple HARQ-ACK signals, an alternative method is to transmit a singleHARQ-ACK signal while selecting the transmission resources to provideadditional degrees of freedom and hence allow for more HARQ-ACKinformation to be implicitly conveyed. For example, if the UE receives asingle TB in each of four DL CCs and each DL CC is linked to a differentUL CC then, by selecting the UL CC where the HARQ-ACK signal istransmitted, the UE can convey 2 HARQ-ACK bits and convey the remaining2 HARQ-ACK bits by applying QPSK modulation to the transmitted HARQ-ACKsignal. Although this CC selection method avoids the shortcomings ofmultiple simultaneous HARQ-ACK signal transmissions, it cannot generallyprovide adequate multiplexing capacity. For example, if the UE receivestwo TBs in any of the four DL CCs, then at least 5 HARQ-ACK bits willneed to be transmitted which is not possible using only UL CC selectionand QPSK modulation. Moreover, having a variable UL CC convey theHARQ-ACK signal transmission is not desirable for implementation andperformance reasons.

Therefore, there is a need to determine transmission methods forHARQ-ACK signals in response to TBs transmitted in multiple DL CCs thatavoid increasing the PAPR and also avoid degrading the receptionreliability of the HARQ-ACK signal while providing the requiredmultiplexing capacity for the transmission of the HARQ-ACK bits.

There is another need to minimize the interference generated by theHARQ-ACK signal transmission and minimize the respective requiredresources by avoiding the transmission of multiple HARQ-ACK signals perUE transmitter antenna.

There is another need to determine rules for applying differentprinciples to the transmission of a single HARQ-ACK signal depending onthe number of HARQ-ACK bits that need to be conveyed.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been designed to solve at leastthe aforementioned limitations and problems in the prior art and thepresent invention provides methods and apparatus for a UE to transmitACKnowledgement signals associated with the use of a Hybrid AutomaticRepeat reQuest (HARQ) process (HARQ-ACK signals) that are in response tothe reception by the UE of Transport Blocks (TBs) transmitted by a NodeB in multiple Component Carriers (CCs).

In accordance with an aspect of the present invention, a method isprovided for transmitting HARQ-ACK information by a terminal in awireless communication system, including receiving one or more transportblocks, including determining a number of HARQ-ACK bits in response tothe one or more transport blocks, determining an uplink resource fortransmission of the HARQ-ACK bits, and transmitting the HARQ-ACK bits byusing the determined uplink resource, wherein the uplink resource isassociated with a first modulation order or with a second modulationorder depending on the number of HARQ-ACK bits, and wherein the firstmodulation order is different from the second modulation order.

In accordance with another aspect of the present invention, a terminalis provided for transmitting HARQ-ACK information in a wirelesscommunication system, including a transceiver, and a controller coupledwith the transceiver and configured to control to receive one or moretransport blocks, determine a number of HARQ-ACK bits in response to theone or more transport blocks, determine an uplink resource fortransmission of the HARQ-ACK bits, and transmit the HARQ-ACK bits byusing the determined uplink resource, wherein the uplink resource isassociated with a first modulation order or with a second modulationorder depending on the number of HARQ-ACK bits, and wherein the firstmodulation order is different from the second modulation order.

In accordance with another aspect of the present invention, a method isprovided for receiving HARQ-ACK information by a base station in awireless communication system, including transmitting one or moretransport blocks, determining a number of HARQ-ACK bits in response tothe one or more transport blocks, determining an uplink resource fortransmission of the HARQ-ACK bits, and receiving the HARQ-ACK bits byusing the determined uplink resource, wherein the uplink resource isassociated with a first modulation order or with a second modulationorder depending on the number of HARQ-ACK bits, and wherein the firstmodulation order is different from the second modulation order.

In accordance with another aspect of the present invention, a basestation is provided receiving HARQ-ACK information by a base station ina wireless communication system, including a transceiver, and acontroller coupled with the transceiver and configured control totransmit one or more transport blocks, determine a number of HARQ-ACKbits in response to the one or more transport blocks, determine anuplink resource for transmission of the HARQ-ACK bits, and receive theHARQ-ACK bits by using the determined uplink resource, wherein theuplink resource is associated with a first modulation order or with asecond modulation order depending on the number of HARQ-ACK bits, andwherein the first modulation order is different from the secondmodulation order.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating an exemplary PUCCH sub-frame structure;

FIG. 2 is a diagram illustrating an exemplary structure for HARQ-ACKsignal transmission in one slot of a PUCCH sub-frame;

FIG. 3 is a block diagram illustrating an exemplary transmitterstructure for a CAZAC sequence;

FIG. 4 is a block diagram illustrating an exemplary receiver structurefor a CAZAC sequence;

FIG. 5 is a diagram illustrating an exemplary multiplexing of CAZACsequences through the application of different cyclic shifts;

FIG. 6 is a block diagram illustrating the PDCCH transmission usingCCEs;

FIG. 7 is a diagram illustrating the availability of different resourcesfor HARQ-ACK signal transmission in an UL CC in response to reception ofTBs in multiple DL CCs;

FIG. 8 is a diagram illustrating the generation of resources forHARQ-ACK signal transmission using the CCEs that convey the SAs for thereception of TBs in multiple DL CCs.

FIG. 9 is a diagram illustrating a first exemplary parameter selectionprocess for the HARQ-ACK signal transmission method depending on thenumber of HARQ-ACK bits; and

FIG. 10 is a diagram illustrating a second exemplary parameter selectionprocess for the HARQ-ACK signal transmission method depending on thenumber of HARQ-ACK bits.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete and willfully convey the scope of the invention to those skilled in the art.

Additionally, although the present invention is described in relation toan Orthogonal Frequency Division Multiple Access (OFDMA) communicationsystem, it also applies to all Frequency Division Multiplexing (FDM)systems in general and to Single-Carrier Frequency Division MultipleAccess (SC-FDMA), OFDM, FDMA, Discrete Fourier Transform (DFT)-spreadOFDM, DFT-spread OFDMA, SC-FDMA, and SC-OFDM in particular.

Methods and apparatus are described for increasing the informationmultiplexing capacity in a single HARQ-ACK signal transmitted from a UEin response to the reception of TBs in multiple DL CCs. It is assumedthat for each DL CC, separate PUCCH resources exist for the HARQ-ACKsignal transmission in response to reception of TBs in the respective DLCC.

The present invention considers that the UE can select the resources forthe transmission of the HARQ-ACK signal based on the value of thetransmitted HARQ-ACK bits. These resources are not necessarily confinedto the ones corresponding to HARQ-ACK signal transmission from a singleDL CC but combinations of resources corresponding to multiple DL CCs canbe used for the transmission of a single HARQ-ACK signal in each of thesub-frame slots. These resources are derived from some or all PDCCH CCEs(not necessarily from only the first CCE) used to transmit the SAsassociated with the reception of TBs over N DL CCs for which HARQ-ACKinformation is subsequently generated and transmitted by the UE to itsserving Node B. For example, for the transmission of SAs associated withthe application of the Multiple Input Multiple Output (MIMO)transmission principle wherein the Node B can convey multiple TBs to aUE in a sub-frame of the same DL CC, the size of the SA is typicallylarge enough so that of 2 PDCCH CCEs can be always assumed for itstransmission. The number of available resources for the transmission ofan HARQ-ACK signal is

$T = {\sum\limits_{j = 1}^{N}{K_{j}\mspace{14mu} {where}\mspace{14mu} K_{j}}}$

where K_(j) is the number of CCEs used for the SA transmission in thej^(th) DL CC, j=1, . . . , N.

In addition, the sub-frame slots may also contribute in the total numberof available resources if either the same CS in each of the L=2sub-frame slots is used for two combinations of HARQ-ACK bits havinglength-2 OCC in each slot or if different HARQ-ACK bits are transmittedin each sub-frame slot as they will be subsequently described.

FIG. 8 further illustrates the concept for generating T=8 UL resourcesfor the transmission by a reference UE of an HARQ-ACK signal is responseto the reception of TBs over N=3 DL CCs, DL CC1 802, DL CC2 804, and DLCC3 806. The SAs associated with the reception of TBs in each of the DLCCs are assumed to be separately encoded and transmitted in therespective DL CC but this is not a limiting aspect of the invention andjoint coding and transmission of the SAs may also be used. In the PDCCHof DL CC1,the SA transmission to the reference UE, UEr 810, is allocatedK₁=2 CCEs, CCE i and CCE i+1 820. The remaining CCEs in the PDCCH of DLCC1 are allocated to other UEs 811A and 811B. In the PDCCH of DL CC2,theSA transmission to the reference UE, UEr 812, is allocated K₂=2 CCEs,CCE k and CCE k+1 822. The remaining CCEs are allocated to other UEs813A and 813B. In the PDCCH of DL CC3,the SA transmission to thereference UE, UEr 814, is allocated K₃=4 CCEs, CCE 1, CCE 1+1, CCE 1+2,and CCE 1+3 824. The remaining CCEs are allocated to other UEs 825A and825B. Using a one-to-one mapping, the CCEs in the PDCCH of DL CC1,thePDCCH of DL CC2,and the PDCCH of DL CC3 are respectively mapped, 830,832, and 834, to the respective UL resources for the transmission ofHARQ-ACK signals, 840 for UEr and 841A and 841B for other UEs, 842 forUEr and 843A and 843B for other UEs, and 844 for UEr and 845A and 845Bfor other UEs. The total resources (RSRC) available for the transmissionof an ACK/NAK channel from the reference UE are {RSRC i, RSRC i+1, RSRCk, RSRC k+1, RSRC i, RSRC i+1, RSRC k, RSRC k+1} for a total of

$T = {{\sum\limits_{j = 1}^{3}K_{j}} = 8}$

resources.

A first mechanism for increasing the multiplexing capacity of a singleHARQ-ACK signal, in terms of the number of HARQ-ACK bits it can conveyper UE, is to allow the same resource to be used in one of the two slotsfor the transmission of different HARQ-ACK bits (the resource may bedifferent in the two slots). Then, for L=2 slots in the exemplaryembodiment, the total number of resource combinations is T^(L). Thetotal number of combinations for the values of M HARQ-ACK bits is 2^(M).Resource selection with QPSK modulation can support the transmission ofM HARQ-ACK bits if 2^(M−2)≤T^(L). Table 1 illustrates the transmissionof M=8 HARQ-ACK bits assuming N=4 DL CCs, K_(j)=2 CCEs (j=1, . . . , N),and L−2 slots for the transmission of the SA in each DL CC. Therefore,T=8, T^(L)=64, and 2^(M−2)=64.

TABLE 1 Mapping of HARQ-ACK Bits to Resources-Single HARQ-ACK SignalTransmission. ACK → −1, NAK → 1 DL CC Link of UL Resources for DL CCLink of UL Resources for Combinations of Bits Transmission in 1^(st)Slot Transmission in 2^(nd) Slot {1, 1, 1, 1, 1, 1} DL CC1, CCE1(Resource 1) DL CC1, CCE1 (Resource 1) {1, 1, 1, 1, 1, −1} DL CC1, CCE1(Resource 1) DL CC1, CCE2 (Resource 2) {1, 1, 1, 1, −1, 1} DL CC1, CCE1(Resource 1) DL CC2, CCE1 (Resource 3) {1, 1, 1, 1, −1, −1} DL CC1, CCE1(Resource 1) DL CC2, CCE2 (Resource 4) {1, 1, 1, −1, 1, 1} DL CC1, CCE1(Resource 1) DL CC3, CCE1 (Resource 5) {1, 1, 1, −1, 1, −1} DL CC1, CCE1(Resource 1) DL CC3, CCE2 (Resource 6) {1, 1, 1, −1, −1, 1} DL CC1, CCE1(Resource 1) DL CC4, CCE1 (Resource 7) {1, 1, 1, −1, −1, −1} DL CC1,CCE1 (Resource 1) DL CC4, CCE2 (Resource 8) {1, 1, −1, 1, 1, 1} DL CC1,CCE2 (Resource 2) DL CC1, CCE1 (Resource 1) {1, 1, −1, 1, 1, −1} DL CC1,CCE2 (Resource 2) DL CC1, CCE2 (Resource 2) {1, 1, −1, 1, −1, 1} DL CC1,CCE2 (Resource 2) DL CC2, CCE1 (Resource 3) {1, 1, −1, 1, −1, −1} DLCC1, CCE2 (Resource 2) DL CC2, CCE2 (Resource 4) {1, 1, −1, −1, 1, 1} DLCC1, CCE2 (Resource 2) DL CC3, CCE1 (Resource 5) {1, 1, −1, −1, 1, −1}DL CC1, CCE2 (Resource 2) DL CC3, CCE2 (Resource 6) {1, 1, −1, −1, −1,1} DL CC1, CCE2 (Resource 2) DL CC4, CCE1 (Resource 7) {1, 1, −1, −1,−1, −1} DL CC1, CCE2 (Resource 2) DL CC4, CCE2 (Resource 8) {1, −1, 1,1, 1, 1} DL CC2, CCE1 (Resource 3) DL CC1, CCE1 (Resource 1) {1, −1, 1,1, 1, −1} DL CC2, CCE1 (Resource 3) DL CC1, CCE2 (Resource 2) {1, −1, 1,1, −1, 1} DL CC2, CCE1 (Resource 3) DL CC2, CCE1 (Resource 3) {1, −1, 1,1, −1, −1} DL CC2, CCE1 (Resource 3) DL CC2, CCE2 (Resource 4) {1, −1,1, −1, 1, 1} DL CC2, CCE1 (Resource 3) DL CC3, CCE1 (Resource 5) {1, −1,1, −1, 1, −1} DL CC2, CCE1 (Resource 3) DL CC3, CCE2 (Resource 6) {1,−1, 1, −1, −1, 1} DL CC2, CCE1 (Resource 3) DL CC4, CCE1 (Resource 7){1, −1, 1, −1, −1, −1} DL CC2, CCE1 (Resource 3) DL CC4, CCE2 (Resource8) {1, −1, −1, 1, 1, 1} DL CC2, CCE2 (Resource 4) DL CC1, CCE1(Resource 1) {1, −1, −1, 1, 1, −1} DL CC2, CCE2 (Resource 4) DL CC1,CCE2 (Resource 2) {1, −1, −1, 1, −1, 1} DL CC2, CCE2 (Resource 4) DLCC2, CCE1 (Resource 3) {1, −1, −1, 1, −1, −1} DL CC2, CCE2 (Resource 4)DL CC2, CCE2 (Resource 4) {1, −1, −1, −1, 1, 1} DL CC2, CCE2 (Resource4) DL CC3, CCE1 (Resource 5) {1, −1, −1, −1, 1, −1} DL CC2, CCE2(Resource 4) DL CC3, CCE2 (Resource 6) {1, −1, −1, −1, −1, 1} DL CC4,CCE2 (Resource 4) DL CC4, CCE1 (Resource 7) {1, −1, −1, −1, −1, −1} DLCC2, CCE2 (Resource 4) DL CC4, CCE2 (Resource 8) {−1, 1, 1, 1, 1, 1} DLCC3, CCE1 (Resource 5) DL CC1, CCE1 (Resource 1) {−1, 1, 1, 1, 1, −1} DLCC3, CCE1 (Resource 5) DL CC1, CCE2 (Resource 2) {−1, 1, 1, 1, −1, 1} DLCC3, CCE1 (Resource 5) DL CC2, CCE1 (Resource 3) {−1, 1, 1, 1, −1, −1}DL CC3, CCE1 (Resource 5) DL CC2, CCE2 (Resource 4) {−1, 1, 1, −1, 1, 1}DL CC3, CCE1 (Resource 5) DL CC3, CCE1 (Resource 5) {−1, 1, 1, −1, 1,−1} DL CC3, CCE1 (Resource 5) DL CC3, CCE2 (Resource 6) {−1, 1, 1, −1,−1, 1} DL CC3, CCE1 (Resource 5) DL CC4, CCE1 (Resource 7) {−1, 1, 1,−1, −1, −1} DL CC3, CCE1 (Resource 5) DL CC4, CCE2 (Resource 8) {−1, 1,−1, 1, 1, 1} DL CC3, CCE2 (Resource 6) DL CC1, CCE1 (Resource 1) {−1, 1,−1, 1, 1, −1} DL CC3, CCE2 (Resource 6) DL CC1, CCE2 (Resource 2) {−1,1, −1, 1, −1, 1} DL CC3, CCE2 (Resource 6) DL CC2, CCE1 (Resource 3){−1, 1, −1, 1, −1, −1} DL CC3, CCE2 (Resource 6) DL CC2, CCE2 (Resource4) {−1, 1, −1, −1, 1, 1} DL CC3, CCE2 (Resource 6) DL CC3, CCE1(Resource 5) {−1, 1, −1, −1, 1, −1} DL CC3, CCE2 (Resource 6) DL CC3,CCE2 (Resource 6) {−1, 1, −1, −1, −1, 1} DL CC3, CCE2 (Resource 6) DLCC4, CCE1 (Resource 7) {−1, 1, −1, −1, −1, −1} DL CC3, CCE2 (Resource 6)DL CC4, CCE2 (Resource 8) {−1, −1, 1, 1, 1, 1} DL CC4, CCE1 (Resource 7)DL CC1, CCE1 (Resource 1) {−1, −1, 1, 1, 1, −1} DL CC4, CCE1 (Resource7) DL CC1, CCE2 (Resource 2) {−1, −1, 1, 1, −1, 1} DL CC4, CCE1(Resource 7) DL CC2, CCE1 (Resource 3) {−1, −1, 1, 1, −1, −1} DL CC4,CCE1 (Resource 7) DL CC2, CCE2 (Resource 4) {−1, −1, 1, −1, 1, 1} DLCC4, CCE1 (Resource 7) DL CC3, CCE1 (Resource 5) {−1, −1, 1, −1, 1, −1}DL CC4, CCE1 (Resource 7) DL CC3, CCE2 (Resource 6) {−1, −1, 1, −1, −1,1} DL CC4, CCE1 (Resource 7) DL CC4, CCE1 (Resource 7) {−1, −1, 1, −1,−1, −1} DL CC4, CCE1 (Resource 7) DL CC4, CCE2 (Resource 8) {−1, −1, −1,1, 1, 1} DL CC4, CCE2 (Resource 8) DL CC1, CCE1 (Resource 1) {−1, −1,−1, 1, 1, −1} DL CC4, CCE2 (Resource 8) DL CC1, CCE2 (Resource 2) {−1,−1, −1, 1, −1, 1} DL CC4, CCE2 (Resource 8) DL CC2, CCE1 (Resource 3){−1, −1, −1, 1, −1, −1} DL CC4, CCE2 (Resource 8) DL CC2, CCE2 (Resource4) {−1, −1, −1, −1, 1, 1} DL CC4, CCE2 (Resource 8) DL CC3, CCE1(Resource 5) {−1, −1, −1, −1, 1, −1} DL CC4, CCE2 (Resource 8) DL CC3,CCE2 (Resource 6) {−1, −1, −1, −1, −1, 1} DL CC4, CCE2 (Resource 8) DLCC4, CCE1 (Resource 7) {−1, −1, −1, −1, −1, −1} DL CC4, CCE2 (Resource8) DL CC4, CCE2 (Resource 8)

If 2^(M−2)>T^(L), or resource sharing by different HARQ-ACK bits in oneof the two slots is not desired, or if only a sub-set of the totalavailable resources should be used in order to avoid more frequent thandesired error events, additional mechanisms can apply for thetransmission of M HARQ-ACK bits. It should be noted that the Node B canchoose to increase the number of CCEs used for the SA transmission insome of the DL CCs in order to increase the value of L and satisfy thecondition 2^(M−2)≤T^(L) or increase its margin if additional mechanismsare either not available or not desired.

A second mechanism for increasing the multiplexing capacity of a singleHARQ-ACK signal, in terms of the number of HARQ-ACK bits it can conveyper UE, is to adapt the modulation order of the transmitted signal. Fora single UE transmitter antenna, the necessary condition for supportingthe transmission of M HARQ-ACK bits over T distinct resources (noresource is shared in any slot of the sub-frame for the transmission ofdifferent HARQ-ACK bits) becomes 2^(M−Q)≤T where Q is the number of bitsthat can be conveyed for a given modulation order (Q=1 for BPSK, Q=2 forQPSK, Q=3 for 8PSK, and Q=4 for QAM 16). For example, assuming N=4 DLCCs with K_(j)=4(j=1, . . . , N) CCEs for the SA transmission and 2 TBstransmitted to the UE per DL CC, the UE needs to transmit M=8 HARQ-ACKbits over T=16 distinct resources. Using QAM 16 modulation, 4 HARQ-ACKbits can be conveyed and each of the 16 combinations for the remaining 4HARQ-ACK bits can be accommodated by the UE respectively selecting oneof the 16 available resources, as shown for example in Table 2.

TABLE 2 Mapping of HARQ-ACK Bits to Resources-Single HARQ-ACK SignalTransmission. ACK → −1, NAK → 1 Combinations of Bits DL CC Link of ULResource {1, 1, 1, 1} DL CC1, CCE1 (Resource 1)  {1, 1, 1, −1} DL CC1,CCE2 (Resource 2)  {1, 1,−1, 1} DL CC1, CCE3 (Resource 3)  {1, 1, −1,−1} DL CC1, CCE4 (Resource 4)  {1, −1, 1, 1} DL CC2, CCE1 (Resource 5) {1, −1, 1, −1} DL CC2, CCE2 (Resource 6)  {1, −1, −1, 1} DL CC2, CCE3(Resource 7)  {1, −1, −1, −1} DL CC2, CCE4 (Resource 8)  {−1, 1, 1, 1}DL CC3, CCE1 (Resource 9)  {−1, 1, 1, −1} DL CC3, CCE2 (Resource 10){−1, 1, −1, 1} DL CC3, CCE3 (Resource 11) {−1, 1,−1, −1} DL CC3, CCE4(Resource 12) {−1, −1, 1, 1} DL CC4, CCE1 (Resource 13) {−1, −1, 1, −1}DL CC4, CCE2 (Resource 14) {−1, −1, −1, 1} DL CC4, CCE3 (Resource 15){−1, −1, −1, −1} DL CC4, CCE4 (Resource 16)

A third mechanism for increasing the multiplexing capacity of a singleHARQ-ACK signal (per antenna), in terms of the number of HARQ-ACK bitsit can convey per UE, applies in case the UE has 2 transmitter antennas(with each antenna having its own power amplifier). Then, the number ofM HARQ-ACK bits can be divided among the two antennas with the firstantenna transmitting ┌M2┐ HARQ-ACK bits using, for example, odd numberedUL resources and the second antenna transmitting └M2┘ HARQ-ACK bitsusing even numbered UL resources, where the ┌ ┐ (ceiling) functionrounds a number to its next integer and the └ ┘ (floor) function roundsa number to its previous integer. Then, the available UL resources aresufficient for transmitting M HARQ-ACK bits using a modulation conveyingQ bits if 2^(┌M/)2┐−−Q≤┌T/2┐ for the first antenna and if2^(└M/2┘−Q)≤└T/2┘ for the second antenna. For example, for T=8 (such asfor N=4 DL CCs with K_(j)=2(j=1, . . . , N) CCEs for the SAtransmission), if M=8 HARQ-ACK bits need to be transmitted (2 TBs foreach of the N=4 DL CCs), the first UE antenna can transmit ┌M/2┐=4HARQ-ACK bits, using for example QPSK modulation for 2 HARQ-ACK bits andresource selection for 2 HARQ-ACK bits, and the second antenna can alsotransmit └M/2┘=4 HARQ-ACK bits using the same approach as for the firstantenna. Nevertheless, different modulation may be used by each the twoUE transmitter antennas (such as QAM 16 for the first antenna and QPSKfor the second antenna). The available resources per antenna are┌T/2┐=└T/2┘=4 and can accommodate the 2^(┌M/2┐−Q)=q^(└M/2┘−Q)=4combinations of the 2 HARQ-ACK bits conveyed through resource selectionper antenna. Table 3 shows an exemplary allocation of the odd numberedresources to the first antenna and of the even numbered resources to thesecond antenna to convey the value of 2 HARQ-ACK bits through resourceselection.

TABLE 3 Mapping Odd/Even Resources to HARQ-ACK Bits from First/Second UEAntenna. ACK → −1, NAK → 1 DL CC Link of UL Resources for DL CC Link ofUL Resources for Combinations of Bits Transmission by First UE AntennaTransmission by Second UE Antenna {1, 1} DL CC1, CCE1 (Resource 1) DLCC1, CCE2 (Resource 2) {1, −1} DL CC2, CCE1 (Resource 3) DL CC2, CCE2(Resource 4) {−1, 1} DL CC3, CCE1 (Resource 5) DL CC3, CCE2 (Resource 6){−1, −1} DL CC4, CCE1 (Resource 7) DL CC4, CCE2 (Resource 8)

A fourth mechanism for increasing the multiplexing capacity of a singleHARQ-ACK channel, in terms of the number of HARQ-ACK bits it can conveyper UE, is to adaptively configure a UE to either use higher ordermodulation, as it was previously described, or to bundle multipleHARQ-ACK bits corresponding to multiple TBs transmitted per DL CC into asingle HARQ-ACK bit. In this manner, UEs with adequately high SINR canstill transmit an HARQ-ACK bit for every received TB using higher ordermodulation while UEs not having adequately high SINR to support higherorder modulation can transmit a single HARQ-ACK bit resulting frombundling the individual HARQ-ACK bits for each TB per DL CC. The bundledHARQ-ACK bit has the value of ACK if all individual bits are ACK and hasthe value of NAK if any of the individual bits is NAK. Bundling ofHARQ-ACK bits per DL CC results to the transmission of a single HARQ-ACKbit per DL CC and M=N.

A fifth mechanism for increasing the multiplexing capacity of a singleHARQ-ACK signal, in terms of the number of HARQ-ACK bits it can conveyper UE per TTI, is to transmit different HARQ-ACK bits in each of theL=2 slots or in each of the two parts of each slot where HARQ-ACK bitsare transmitted. In the first case, the UE transmits the same HARQ-ACKbits in each slot but different HARQ-ACK bits per slot. In the secondcase, the UE transmits different HARQ-ACK bits in each half of each slot(using length-2 OCC, instead of length-4 OCC) and the same HARQ-ACK bitsin both slots. Then, the available UL resources are sufficient fortransmitting M HARQ-ACK bits using a modulation conveying Q bits in eachslot is 2^(┌M/2┐−Q)≤T. If different HARQ-ACK bits are transmitted iseach half of each slot, then the available UL resources are sufficientfor transmitting M HARQ-ACK bits using a modulation conveying Q bits ineach slot if 2^(┌M/4┐−Q)≤T.

Although, for simplicity, the HARQ-ACK signal is assumed to use the samemodulation scheme in each slot or in each half of each slot, this is notnecessary and different modulation schemes may instead be used. Forexample, for T=10 (such as for N=10 DL CCs with K_(j)=2(j=1, . . . , N)CCEs for the SA transmission), if M=10 HARQ-ACK bits need to betransmitted (2 TBs transmitted in each DL CC), the first 5 bits can betransmitted in the first slot, or in the first half of the first slot,and the second 5 bits can be transmitted in the second slot, or in thesecond half of each slot, using QPSK to convey the first 2 of the 5 bitsand using resource selection among the T=10 resources to convey the last3 of the 5 bits in each slot. Table 4 shows an exemplary resourceselection to convey 3 HARQ-ACK bits in the first slot (the same resourceselection setup can apply to convey 3 HARQ-ACK bits in the second slot).

TABLE 4 Mapping HARQ-ACK Bits to Resources-HARQ-ACK Signal Transmissionin One Slot. ACK → −1, NAK → 1 Combinations of Bits DL CC Link of ULResource {1, 1, 1} DL CC1, CCE1 (Resource 1) {1, 1, −1} DL CC1, CCE2(Resource 2) {1, −1, 1} DL CC2, CCE1 (Resource 3) {1, −1, −1} DL CC2,CCE2 (Resource 4) {−1, 1, 1} DL CC3, CCE1 (Resource 5) {−1, 1, −1} DLCC3, CCE2 (Resource 6) {−1, −1, 1} DL CC4, CCE1 (Resource 7) {−1, −1,−1} DL CC4, CCE2 (Resource 8)

Among the previously described mechanisms for the transmission of asingle HARQ-ACK signal, an exemplary decision process in case of asingle UE transmitter antenna is described in FIG. 9 and is as follows:

-   a) Configure per UE maximum modulation order for HARQ-ACK signal    transmission 910.-   b) The UE determines the smallest modulation order satisfying    2^(M−Q)≤T 920 and determines if it belongs in the allowable    modulation orders the UE is configured 925.

a. If 2^(M−Q)≤T 930, the UE transmits the HARQ-ACK signal with theselected modulation order and using resource selection as it waspreviously described 940 (different combinations of HARQ-ACK bits usedifferent resources in all slots).

b. If 2^(M−Q)>T 950 for all allowable modulation orders, the UE can beconfigured to perform any combination of the following:

-   *64 i. Allow combinations of HARQ-ACK bits to share the same    resource in one of the L=2 transmission slots 960. Then, the second    step is repeated with the condition 2^(M−Q)≤T^(L) replacing    2^(M−Q)≤T.

ii. Bundle multiple HARQ-ACK bits respectively corresponding to multipleTBs received by the UE per DL CC 970. Then, using the new numberM_(bundle) of HARQ-ACK bits resulting after bundling, the second step isrepeated with the condition 2^(┌M/2┐−Q)≤T replacing 2^(M−Q)≤T.

iii. Transmit (partly or completely) different HARQ-ACK bits in the L=2transmission slots 980. Then, the second step is repeated with thecondition 2^(┌M/2┐−Q)≤T replacing 2^(M−Q)≤T.

If the UE has 2 transmitter antennas, an exemplary decision process isdescribed in FIG. 10 and is as follows:

-   a) Configure per UE a maximum modulation order for HARQ-ACK signal    transmission 1010.-   b) The UE determines the smallest modulation order satisfying    2^(M−Q)≤└T/2┘ 1020 and determines if it belongs in its allowable    modulation orders the UE is configured 1025.

a. If 2^(M−Q)≤└T/2┘ 1030 and the UE is configured transmitter antennadiversity, the UE signals the HARQ-ACK bits from the first antenna usinga first resource from a first set of resources and signals the sameHARQ-ACK bits from the second antenna using a second resource from asecond set of resources 1035, wherein the first set and second set ofresources do not any common element.

b. If 2^(M−Q)>└T/2┘ 1040, the UE examines if 2^(┌M/2┐−Q)≤┌T/2┐ and2^(└M/2┘−Q)≤└T/2┘ 1045.

i. If 2^(┌M/2┐−Q)≤┌T/2┐ and 2^(└M/2┘−Q)≤└T/2┘ 1050, the UE transmits afirst HARQ-ACK signal conveying ┌M/2┐ HARQ-ACK bits in a first set ofresources using the first transmitter antenna and transmits a secondHARQ-ACK signal conveying └M/2┘ HARQ-ACK bits in a second set ofresources using the second transmitter antenna 1055, wherein the firstset and second set of resources do not any common element.

ii. If 2^(┌M/2┐−Q)>┌T/2┐ or 2^(└M/2┘−Q)>└T/2┘ 1060, the UE can beconfigured to perform any combination of the following:

1. Allow combinations of HARQ-ACK bits to share the same resource in oneof the L transmission slots (in the exemplary embodiment L=2) 1070.Then, the second step is repeated with the condition 2^(M−Q)≤└T/2┘^(L)replacing 2^(M−Q)≤└T/2┘.

2. Bundle multiple HARQ-ACK bits respectively corresponding to multipleTBs received by the UE per DL CC 1080. Then, using the new number MofHARQ-ACK bits resulting after bundling, the second step is repeated withthe condition 2^(M) ^(bundle) ^(−Q)≤└T/2┘ replacing 2^(M−Q)≤└T/2┘.

3. Transmit (partly or completely) different HARQ-ACK bits in the L=2transmission slots 1090. Then, the second step is repeated with thecondition 2^(┌M/2┐−Q)≤└T/2┘ replacing 2^(M−Q)≤└T/2┘.

While the present invention has been shown and described with referenceto certain preferred embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention as defined by the appended claims.

What is claimed is:
 1. A method for transmitting hybrid automatic repeatrequest acknowledgement (HARQ-ACK) information by a terminal in awireless communication system, the method comprising: receiving one ormore transport blocks; determining a number of HARQ-ACK bits in responseto the one or more transport blocks; determining an uplink resource fortransmission of the HARQ-ACK bits; and transmitting the HARQ-ACK bits byusing the determined uplink resource, wherein the uplink resource isassociated with a first modulation order or with a second modulationorder depending on the number of HARQ-ACK bits, and wherein the firstmodulation order is different from the second modulation order.
 2. Themethod of claim 1, wherein the one or more transport blocks comprises afirst transport block and a second transport block, and wherein thefirst transport block is received on a first downlink carrier and thesecond transport block is received on a second downlink carrier.
 3. Themethod of claim 1, wherein determining the uplink resource comprises:determining the uplink resource as a first uplink resource associatedwith the first modulation order for transmission of the HARQ-ACK bits,in response to the number of HARQ-ACK bits having a first number ofbits; and determining the uplink resource as a second uplink resourceassociated with the second modulation order for transmission of theHARQ-ACK bits, in response to the HARQ-ACK signal having a second numberof bits.
 4. A terminal for transmitting hybrid automatic repeat requestacknowledgement (HARQ-ACK) information in a wireless communicationsystem, the terminal comprising: a transceiver; and a controller coupledwith the transceiver and configured to control to: receive one or moretransport blocks, determine a number of HARQ-ACK bits in response to theone or more transport blocks, determine an uplink resource fortransmission of the HARQ-ACK bits, and transmit the HARQ-ACK bits byusing the determined uplink resource, wherein the uplink resource isassociated with a first modulation order or with a second modulationorder depending on the number of HARQ-ACK bits, and wherein the firstmodulation order is different from the second modulation order.
 5. Theterminal of claim 4, wherein the one or more transport blocks comprisesa first transport block and a second transport block, and wherein thefirst transport block is received on a first downlink carrier and thesecond transport block is received on a second downlink carrier.
 6. Theterminal of claim 4, wherein the controller is further configured to:determine the uplink resource as a first uplink resource associated withthe first modulation order for transmission of the HARQ-ACK bits, inresponse to the number of HARQ-ACK bits having a first number of bits;and determine the uplink resource as a second uplink resource associatedwith the second modulation order for transmission of the HARQ-ACK bits,in response to the HARQ-ACK signal having a second number of bits.
 7. Amethod for receiving hybrid automatic repeat request acknowledgement(HARQ-ACK) information by a base station in a wireless communicationsystem, the method comprising: transmitting one or more transportblocks; determining a number of HARQ-ACK bits in response to the one ormore transport blocks; determining an uplink resource for transmissionof the HARQ-ACK bits; and receiving the HARQ-ACK bits by using thedetermined uplink resource, wherein the uplink resource is associatedwith a first modulation order or with a second modulation orderdepending on the number of HARQ-ACK bits, and wherein the firstmodulation order is different from the second modulation order.
 8. Themethod of claim 7, wherein the one or more transport blocks comprises afirst transport block and a second transport block, and wherein thefirst transport block is received on a first downlink carrier and thesecond transport block is received on a second downlink carrier.
 9. Themethod of claim 1, wherein determining the uplink resource comprises:determining the uplink resource as a first uplink resource associatedwith the first modulation order for transmission of the HARQ-ACK bits,in response to the number of HARQ-ACK bits having a first number ofbits; and determining the uplink resource as a second uplink resourceassociated with the second modulation order for transmission of theHARQ-ACK bits, in response to the HARQ-ACK signal having a second numberof bits.
 10. A base station for receiving hybrid automatic repeatrequest acknowledgement (HARQ-ACK) information by a base station in awireless communication system, the base station comprising: atransceiver; and a controller coupled with the transceiver andconfigured control to: transmit one or more transport blocks, determinea number of HARQ-ACK bits in response to the one or more transportblocks, determine an uplink resource for transmission of the HARQ-ACKbits, and receive the HARQ-ACK bits by using the determined uplinkresource, wherein the uplink resource is associated with a firstmodulation order or with a second modulation order depending on thenumber of HARQ-ACK bits, and wherein the first modulation order isdifferent from the second modulation order.
 11. The base station ofclaim 10, wherein the one or more transport blocks comprises a firsttransport block and a second transport block, and wherein the firsttransport block is received on a first downlink carrier and the secondtransport block is received on a second downlink carrier.
 12. The basestation of claim 10, wherein the controller is further configured to:determine the uplink resource as a first uplink resource associated withthe first modulation order for transmission of the HARQ-ACK bits, inresponse to the number of HARQ-ACK bits having a first number of bits;and determine the uplink resource as a second uplink resource associatedwith the second modulation order for transmission of the HARQ-ACK bits,in response to the HARQ-ACK signal having a second number of bits.